The present invention generally relates to a socket assembly that is designed to reduce bowing during actuation.
Pin grid array (PGA) sockets are used to accept electronic packages on printed circuit boards. PGA sockets facilitate electrical communication between a large number of pins born on an electronic processor and electrical components to which the PGA sockets are mounted (such as circuit boards). Zero insertion force (ZIF) PGA sockets utilize a cover that is slidably movable on a base between open and closed positions. The sliding movement may be actuated, for example, by a cam that is rotated by a hand tool. The cover has a hole array configured to match a pin array on a processor. Similarly, the base has an array of pin receiving chambers configured to accept the pin array of the processor. The processor is mated to the socket by first placing the processor such that its pins penetrate the holes of the cover. With the cover in the open position, the pins penetrate through the holes of the cover and into the pin receiving chambers of the base but are not electrically connected to the pin receiving chambers of the base. When the cover is slid to the closed position, the pins are electrically connected to the base via the pin receiving chambers.
Because there may be hundreds of pins in the array, moving the cover to the closed position can require a considerable force to move the pins into their fully mated position. This force can cause the socket assembly to bow, resulting in inadequate actuation and/or de-actuation.
FIG. 1 illustrates an example of a prior art socket system 10 with a cam actuation mechanism. The socket system 10 includes a cover 12 slidably mounted to a housing 14. The housing 14 is mounted to a board (not shown) by solderballs 16. The socket system 10 includes a cam 18 that is accepted by both the cover 12 and the housing 14. Rotation of the cam 18 results in the cover 12 moving along direction A relative to the housing 14. The cover 12 moves to the right in FIG. 1 when closed (or actuation) and to the left when opened (or de-actuation). The socket system 10 also includes a housing wear plate 20 that nests in the housing 14 and contacts the cam 18 along a bearing surface of the cam 18 as the cam 18 is rotated, and a cover wear plate 21 that nests in the cover 12 and also contacts the cam 18 along a bearing surface as the cam 18 is rotated. The cam 18 includes an eccentric portion that contacts the cover wear plate 21, causing the cover 12 to move laterally as the cam 18 is rotated.
When the cam 18 is rotated, resultant forces are exerted on the housing 14 from the cam 18 via the housing wear plate 20. When the cover 12 is being actuated, a resultant force occurs at closing push surface 22. When the cover 12 is being de-actuated, a resultant force occurs at opening push surface 24. These resultant forces create a moment about the solderballs 16 at which the housing 14 is mounted. The horizontal portions of the moment arms are the opening moment arm 26 and the closing moment arm 28, and correspond to the opening push surface 24 and closing push surface 22, respectively. The moments caused by the resultant forces cause bowing and deflection along bowing direction B. Further, the resultant forces at the opening push surface 24 can cause wear and cracking at a back edge 30 of the housing 14.
For the socket system 10 illustrated in FIG. 1, closing or actuation causes deflection downward along bowing direction B. In this circumstance, the socket system 10 may be supported by a board to which it is mounted and engagement may be achieved. However, opening or de-actuation causes bowing upward along bowing direction B. Because there is no support available above the socket system 10, the resulting bowing can prevent disengagement of the socket.
A need remains for a socket assembly that overcomes the above-noted and other disadvantages of existing PGA sockets.
At least one preferred embodiment of the present invention is provided including a socket assembly for receiving electronic packages. The socket assembly includes a cover and a base slidably engaging one another and movable between open and closed positions. The base includes a contact array. The socket assembly also includes a cam member received by the cover and base. Rotation of the cam member actuates a sliding motion between the cover and base. The socket assembly also includes a load bearing member mounted to one of the cover and base. The socket assembly further includes a wear plate mounted about the load bearing member. The wear plate has a cam reception hole accepting the cam member. The load bearing member and the cam member are located different distances from the contact array to reduce the moment caused by the sliding motion between the cover and base.
Optionally, the load bearing feature may extend from a wear plate cavity formed in the base. The distance between the cam member and the contact array is greater than the distance between the load bearing member and the contact array. The load bearing member may include an opening push surface and a closing push surface. The opening push surface transmits a resultant force when the cover is moved toward the open position, and the closing push surface transmits a resultant force when the cover is moved toward the closed position.
The load bearing member may include an oblong raised element including an opening push surface and a closing push surface on opposing sides of the load bearing member. The wear plate may include an opening forming an oblong slot accepting the oblong raised element. The opening includes an opening surface contacting the opening push surface of the load bearing member, and a closing surface contacting the closing push surface of the load bearing member.
In accordance with at least one preferred embodiment, a socket assembly is provided including a housing, a cover, a cam pin, and a housing wear plate. The housing includes an array of contacts. The contacts are mountable to a circuit board at a mounting feature. The housing also includes an opening push surface and closing push surface. The cover is slidably mounted to the housing and movable relative to the housing between an actuated and a de-actuated position. The housing includes a pin grid corresponding to the array of contacts. The cam pin is received by the housing and the cover, and rotation of the cam pin moves the cover between the actuated and de-actuated positions. The cam pin is located farther from the array of contacts than the opening and closing push surfaces. The housing wear plate includes a cam reception hole that receives the cam pin. The cam reception hole has a bearing surface that contacts the cam pin. The housing wear plate transfers actuation forces from the cam pin to the opening and closing push surfaces. The housing wear plate cooperates with the opening push surface and the closing push surface to reduce a resultant moment caused by a sliding motion between the cover and the base.
Optionally, the housing may include a load bearing member extending from a housing wear plate cavity that is formed in the housing. The load bearing member includes at least one of the opening push and closing push surfaces. The housing wear plate includes an opening including at least one of the opening and closing surfaces. The opening receives the load bearing member. The opening may extend through the housing wear plate.
In accordance with at least one preferred embodiment, a socket assembly is provided including a housing, a cover, a cam pin, a cover wear plate, and a housing wear plate. The housing includes an array of contacts that are mountable to a circuit board at a mounting feature. The housing also includes a housing wear plate cavity including a load bearing member extending from the housing wear plate cavity. The load bearing member has an opening push surface and a closing push surface. The cover is slidably mounted to the housing and movable between an actuated and de-actuated position. The cover includes a pin grid corresponding to the array of contacts. The housing and the cover receive the cam pin, and rotation of the cam pin actuates the housing between the actuated and the de-actuated positions. The cam pin is located further from the mounting feature than the opening and closing push surfaces. The cover wear plate is received by the cover and includes a cam reception hole having a bearing surface that contacts the cam pin. The cover wear plate cooperates with the cam pin to transmit resultant forces from the movement of the cover from the cover to the cam pin. The housing wear plate is received by the housing wear plate cavity and has a cam reception hole that receives the cam pin. The cam reception hole has a bearing surface that contacts the cam pin. The housing wear plate includes an opening that includes an opening surface corresponding to the opening push surface of the load bearing member, and a closing surface corresponding to the closing push surface of the load bearing member. The opening receives the load bearing member. The opening and closing surfaces cooperate with the opening push and closing push surfaces, respectively, to reduce the resultant moment cause by the sliding motion between the cover and the base.
Certain embodiments of the present invention thus provide a socket assembly that reduces bowing and improves actuation and de-actuation effectiveness. Certain embodiments of the present invention also provide a socket assembly that reduces wear, damage, and cracking to components of the socket assembly.